LC Displays: It All Comes Down to the Mix

Liquid crystals are key components of modern displays, but they must be optimized for each application. EMD's Taiwan lab handles liquid crystal optimization for Innolux, a top global LC display manufacturer.

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SINCE THE MID-1990S, CATHODE RAY TUBES HAVE BEEN REPLACED BY LC DISPLAYS

These displays have become not only thinner but also larger, with faster switching times, sharper images and brighter colors.

Mobile electronic devices, elegant televisions and computers would not be possible without liquid crystals. They can modulate a backlight with such precision that the colors and pictures presented on the screen have a truly impressive effect. “In developing and producing these displays,” says Chung-Kuang Wei, “the most important goal is to create the perfect balance between performance and cost.”

Dr. Wei, a physicist, is Associate Vice President of the technology center of Innolux, which is located in the southern Taiwanese city of Tainan. Innolux is the third-largest manufacturer of LC displays.

The company’s approximately 93,000 employees provide today’s electronics with a face, one that is based on liquid crystal technology. The fact that materials could have a liquid crystal state was discovered more than 100 years ago. In this state, materials function as optical switches when an electric field is applied: light on, light off. A standard ultra high definition television — UHDTV — has around eight million of these switches. Due to its more than 4,000 columns and over 2,000 rows, UHDTV is also known as 4K2K.

It all comes down to the mix

Only one gram

“We get high–quality, innovative liquid crystals from Merck KGaA, Darmstadt, Germany,” says Chung-Kuang Wei. “Thanks to the location of its laboratory in Taoyuan near Taipei, the capital of Taiwan, the distances and development times are fairly short, as you can imagine.” Karl Skjonnemand, the physicist who is head of liquid crystal research and development in Taoyuan, is also pleased with the situation.

“The manufacturers only require about one gram of liquid crystals per 32 inch display,” he says, “but the properties of the LCs strongly influence the entire impression of the image on the display.” Skjonnemand is a native of the United Kingdom who has been fascinated by Taiwan since he arrived there in 2011. In their research and development activities, Skjonnemand and his team strive every day to further improve LC properties for Taiwanese customers.

This work requires a high level of precision and optimization based on a deep understanding of the liquid crystal materials and how customers use them in display manufacturing. “We receive the base material, known as singles, from Darmstadt,” he explains. These “singles” are combined with up to 20 other compounds very precisely in order to create the exact characteristics desired by the customer.

The basic material specifications determine the performance of the LC display, but Merck KGaA, Darmstadt, Germany goes further, optimizing the LC materials to be compatible with all the other materials and components used in the display’s manufacture. This is a carefully controlled balance between pure performance, usability and reliability.

The most important goal is to create the perfect balance between performance and cost.

Chung-Kuang Wei

Associate Vice President

Innolux Technology Center

With continuous improvements in speed, sharpness and color intensity, modern displays wouldn’t be possible without liquid crystals.

How optimization happens

To meet customers’ technical specifications, Merck KGaA, Darmstadt, Germany first designs new concept materials using its own highly developed simulation tools. It then manufactures small samples, which are precisely measured using many physical and chemical techniques, many of which are designed by Merck KGaA, Darmstadt, Germany itself. The LCs are then re-optimized until Merck KGaA, Darmstadt, Germany is satisfied that it has achieved the best solution for its customers. This is all done in very close cooperation with the customers’ R&D teams, with whom Merck KGaA, Darmstadt, Germany shares concepts, ideas and performance data before sampling the best materials for its own evaluation.

In addition, EMD’s lab in Taiwan heavily stresses the materials to understand how they will perform in the long term once the product is launched and ‘abused’ for years by end users. Once the performance is confirmed by the customer’s R&D, pilot line trials are arranged where the customer makes real LCD panels using the new materials on their mass production lines.

“We cut open the displays,” explains Skjonnemand, “in order to see what is going right and wrong in production.” The physicist is more than just a prosaic scientist, though. “It breaks my heart every time we destroy a 55-inch TV, but this is entirely necessary to improve the technology,” he says. Once the line trials are passed, the materials are then applied to different models, which can have different requirements due to subtle differences in the production equipment, processes, LCD panel structure, and end application requirements.

A tremendous pace of development

EMD’s development of LC materials targets these differences and provides innovative material solutions to their customers. LCD manufacturing is heavily cost-driven, so one of the most important goals is to develop new materials that improve production efficiency. For example, manufacturers now want to use a new type of UV lamp to reduce the amount of time it takes to process the LC materials.

“By developing new LC materials to be compatible with UV lamps of differing spectrums, we dramatically increased the capacity of our customers’ factories. Having a local presence in Taiwan, we were able to react extremely fast and qualify completely new material concepts suitable for more efficient production in just a few months.”

“The pace of development is tremendous,” confirms Chung-Kuang Wei. What is driving this development? The answer is strong competition, new technologies, and new materials. “Today’s displays cost about the same as displays cost several years ago,” he says, “but the ones today are bigger and have deeper color saturation. Ours even have 3D functionality.”

Moreover, they are becoming steadily larger. The 4K2K standard could soon be followed by 8K4K, with 32 million pixels. “The new generation of curved displays, which provide the user with a constant viewing distance across the entire width of the screen, requires a complete redevelopment of the display’s periphery,” he adds.

He is referring to another task being undertaken by Innolux, which regards itself as not only a supplier of displays, but also a comprehensive integrator and pacesetter in the industry. The development of the 4K2K display took about one year. “At the beginning of a new project, we have many possible options. From these we systematically filter out the most promising ones.”

This process is simplified through the comprehensive evaluation of millions of data points ranging from technical parameters and market research, to sustainable environmental policies for development, production, and logistics. “And for all of these factors we always have to consider the effect on price,” adds Chung-Kuang Wei. “Will the consumer be prepared to pay a specific price for a specific level of quality?”

A long lifespan is a must

During the “backlight test,” mini-displays are exposed to the lighting conditions found in televisions. New liquid-crystal mixtures are tested for thousands of hours in order to ensure the necessary service life.

Why Taiwan?

Questions upon questions — and the answers to them will determine the future of this capital-intensive industry, which is highly concentrated in Taiwan due to a combination of special factors. As Chung-Kuang Wei explains, “Taiwanese culture is centered on the family and places a high value on education and hard work. Our biggest resources are knowledge and manpower, and the state has promoted the development of these resources with the goal of encouraging industry.” The success of this policy has created a cluster of companies that are innovative, efficient, and able to manufacture products for a reasonable price. That creates a bright picture for future displays.

About Innolux corporation

Innolux Corporation is one of the world leading TFT-LCD total solution manufacturers, having strong presence in both large-size panels and small & medium size products.

As a world's top panel supplier, Innolux provides the most complete and flexible production lines: twelve TFT-LCD fabs and three touch sensor fabs located in Jhunan and Tainan in Taiwan; along with extensive assembly facilities in China, including in Nanjing, Nanhai, Ningbo and Shanghai.

As a world's top panel supplier, Innolux provides the most complete and flexible production lines: twelve TFT-LCD fabs and three touch sensor fabs located in Jhunan and Tainan in Taiwan; along with extensive assembly facilities in China, including in Nanjing, Nanhai, Ningbo and Shanghai.

EMD’s lab in Taiwan

Merck KGaA, Darmstadt, Germany established a local LC R&D lab and LC production in Taiwan in 2004. In 2013, Merck KGaA, Darmstadt, Germany extended its local capability beyond LCs with an applications laboratory for new technology, thereby supporting the high concentration of high tech manufacturers in Taiwan.

Starting very early on in a product’s development cycle, Merck KGaA, Darmstadt, Germany collaborates closely with the research and development departments of these companies.

Merck KGaA, Darmstadt, Germany delivers rapid and comprehensive support not only for compounds used in the manufacture of all types of LC and OLED displays, but also for the compounds’ use in production — including the promising new inkjet technology.

This method of production works similarly to inkjet printers in that it builds the individual pixels through the high-precision placement of individual droplets of material.

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